Case with ballistic liner

ABSTRACT

A case for a gas turbine engine includes a plurality of distinct case sections in axial series. The case sections include, in axial order, a flange section, a forward shell section, a containment section, and an aft shell section. The forward shell section, the containment section, and the aft shell section are formed of a plurality of unidirectional roving fiber layers and a plurality of non-crimp fabric layers. The flange section is formed of a second plurality of non-crimp fabric layers. The plurality of unidirectional roving fiber layers do not have stitching or weaves. A ballistic liner is attached with the containment section, and a fiberglass layer encapsulates the plurality of unidirectional roving fiber layers, the plurality of non-crimp fabric layers, and the second plurality of non-crimp fabric layers.

This application is a continuation of U.S. patent application Ser. No.13/397,772 filed Feb. 16, 2012.

BACKGROUND

The present disclosure relates to gas turbine engines, and inparticular, to a fan case for a gas turbine engine.

The fan section of a gas turbine engine includes an array of fan bladeswhich project radially from a hub within a fan case. Althoughexceedingly unlikely, it is possible for a fan blade or a fragmentthereof to separate from the hub and strike the fan case. The fan caseoperates to prevent any liberated material from radially exiting theengine. The demands of blade containment are balanced by the demands forlow weight and high strength.

SUMMARY

A case for a gas turbine engine according to an exemplary aspect of thepresent disclosure includes a containment section with a plurality ofunidirectional roving fiber layers and a plurality of non-crimp fabriclayers.

A method of manufacturing a case for a gas turbine engine according toan exemplary aspect of the present disclosure includes winding aplurality of unidirectional roving fiber layers around a plurality ofnon-crimp fabric layers.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features will become apparent to those skilled in the art fromthe following detailed description of the disclosed non-limitingembodiment. The drawings that accompany the detailed description can bebriefly described as follows:

FIG. 1 is a schematic cross-sectional view of a gas turbine engine;

FIG. 2 is an enlarged cross-sectional view of a case of the gas turbineengine which provides blade containment according to one non-limitingembodiment;

FIG. 3 is one layer of the case of the gas turbine engine to illustratea unidirectional roving fiber layer arranged at 0 degree direction;

FIG. 4 is one layer of the case of the gas turbine engine to illustratea non-crimp fabric layer; and

FIG. 5 is one layer of the case of the gas turbine engine to illustratea unidirectional roving fiber layer arranged at 90 degree direction.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a gas turbine engine 20. The gasturbine engine 20 is disclosed herein as two-spool turbofan thatgenerally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. Alternative engines mightinclude an augmentor section (not shown) among other systems orfeatures. The fan section 22 drives air along a bypass flowpath whilethe compressor section 24 drives air along a core flowpath forcompression and communication into the combustor section. Althoughdepicted as a two-spool, turbofan gas turbine engine in the disclosednon-limiting embodiment, it should be understood that the conceptsdescribed herein are not limited to use with two-spool or turbofan asthe teachings can be applied to other turbine engine architectures ortypes.

The engine 20 generally includes a low speed spool 30 and a high speedspool 32 mounted for rotation about an engine central longitudinal axisA relative to an engine static structure 36 via several bearing systems38. The low speed spool 30 generally includes an inner shaft 40 thatinterconnects a fan 42, a low pressure compressor 44 and a low pressureturbine 46. The inner shaft 40 may drive the fan 42 either directly orthrough a geared architecture 48 to drive the fan 42 at a lower speedthan the low speed spool 30. The high speed spool 32 includes an outershaft 50 that interconnects a high pressure compressor 52 and a highpressure turbine 54. A combustor 56 is arranged between the highpressure compressor 52 and the high pressure turbine 54. The inner shaft40 and the outer shaft 50 are concentric and rotate about the enginecentral longitudinal axis A which is collinear with their longitudinalaxes.

Core airflow is compressed by the low pressure compressor 44 then thehigh pressure compressor 52, mixed and burned with the fuel in thecombustor 56, then expanded over the high pressure turbine 54 and lowpressure turbine 46. The turbines 54, 46 rotationally drive therespective low speed spool 30 and high speed spool 32 in response to theexpansion.

With reference to FIG. 2, the fan section 22 includes a fan case 60axially defined into a flange section 62, a forward shell section 64, acontainment section 66, and an aft shell section 68 along axis A. Itshould be understood that alternative or additional sections may bedefined. The fan case 60 combines a plurality of composite materialforms in a plurality of circumferential layers to form a containmentsystem that is lightweight and efficient. It should be understood thatthe particular fibers include but are not limited to carbon, fiberglass,aramid, etc. and the particular resins include but are not limited toEpoxy, BMI, Polyimides, etc.

The containment section 66 generally includes a plurality ofunidirectional roving fiber layers 70 (one layer shown in FIG. 3) and aplurality of non-crimp fabric layers 72 (one layer shown in FIG. 4).Generally, each of the plurality of unidirectional roving fiber layers70 is about half the thickness of each of the plurality of non-crimpfabric layers 72. In the disclosed non-limiting embodiment, each of theplurality of unidirectional roving fiber layers 70 includes three pliesand each of the plurality of non-crimp fabric layers 72 includes twoplies in the containment section 66.

The unidirectional roving fiber layers 70 may include a plurality ofplies of tape or tows. As generally understood, a tow is a plurality offilaments and a tape is a collection of tows. Each ply within theunidirectional roving fiber layers 70 as defined herein are a collectionof fiber tows oriented in the same direction. Typically these are woundaround a mandrel and do not have stitching or weaves.

Each of the plurality of unidirectional roving fiber layers 70 arearranged at either a 0 degree or 90 degree direction with respect to theengine axis A. The 0 degree unidirectional roving fiber layers 70 arewound around the engine axis A to define a 0 degree direction to form ahoop around the engine axis A (FIG. 3). The 90 degree unidirectionalroving fiber layers 70 are, for example, laid up by hand via standardalignment techniques. At least one of the plurality of unidirectionalroving fiber layers 70 may also be oriented along the engine axis A todefine a 90 degree direction (one layer shown in FIG. 5) to facilitatestiffness.

Each of the plurality of non-crimp fabric layers 72 includes two plies72A, 72B (FIG. 4). A first ply 72A is arranged at a +θ orientation andthe second ply 72B at a −θ orientation. θ is an angle defined herein tobe between 0-80 degrees with respect to an engine longitudinal axis Aand may most preferably be 45 degrees. As defined herein, non-crimpfabric may be reinforced mats of straight (non-crimped) fibers, toprovide advantageous strength, ease of handling and low manufacturingcosts.

Within the containment section 66, the plurality of unidirectionalroving fiber layers define approximately 25% of a thickness while theplurality of non-crimp fabric layers define approximately 75% of thethickness. Within the forward shell section 64 and the aft shell section68 the plurality of unidirectional roving fiber layers also defineapproximately 25% of a thickness while the plurality of non-crimp fabriclayers define approximately 75% of the thickness but the shell sections64, 68 are typically of a thinner thickness which in one example, is0.25 inches (6.4 mm) thick while the containment section is 0.5 inches(12.7 mm) thick. It should be appreciate that this thickness is for butone disclosed non-limiting embodiment and that other case structureswill benefit herefrom.

The fan case 60 may further include one or more fiberglass layers 74which essentially encapsulates the plurality of unidirectional rovingfiber layers 70 and the plurality of non-crimp fabric layers 72. Thefiberglass layer 74 may be of various weights to facilitate finalshaping of the fan case 60 such as in the flange section 62. That is,the fiberglass layer 74 protects the other layers therein as well asfacilitates the final outer mold line definition through, for example, amachining operation.

The flange section 62 in accords with one non-limiting embodiment isformed entirely of non-crimp fabric layers 72 which may be encapsulateby the fiberglass layer 74. That is, no unidirectional roving fiberlayers 70 are included in the flange section 62.

The containment section 66 also includes an inner ballistic liner 76defined about the axis A. The inner ballistic liner 76 need only extenda relatively short axial length as the inner ballistic liner 76 isradially located directly outboard of the fan blades 42B of the fan 42(FIG. 1). The inner ballistic liner 76 resists and dulls the ballisticthreat which may be particularly acute with metallic fan blades andprovides a light weight approach manufactured with composite materialsto provide effective containment capability.

The inner ballistic liner 76 may be formed of a plurality of layers of aballistic material such as a resin impregnated aramid fiber material.The inner ballistic liner 76 provides an inner cylindrical shell whichis secondarily bonded or co-cured with the plurality of unidirectionalroving fiber layers 70, the plurality of non-crimp fabric layers 72 andthe inner fiberglass layer 74 which define a composite outer casestructure 78 that replaces the heretofore relatively heavy metal alloystructure.

In addition, an abradable layer 80 radially inboard of the innerballistic liner 76 provides close tolerances with tips of the fan blade42B. Additional aerodynamic liners 82, 84 manufactured at leastpartially of a honeycomb, acoustic absorbant or other materials may belocated axially forward and axially aft of the abradable liner 80. Itshould be appreciated that additional or alternative structures and ormaterials may be utilized with the outer case structure 78.

It should be understood that like reference numerals identifycorresponding or similar elements throughout the several drawings. Itshould also be understood that although a particular componentarrangement is disclosed in the illustrated embodiment, otherarrangements will benefit herefrom.

Although particular step sequences are shown, described, and claimed, itshould be understood that steps may be performed in any order, separatedor combined unless otherwise indicated and will still benefit from thepresent invention.

The foregoing description is exemplary rather than defined by thelimitations within. Various non-limiting embodiments are disclosedherein, however, one of ordinary skill in the art would recognize thatvarious modifications and variations in light of the above teachingswill fall within the scope of the appended claims. It is therefore to beunderstood that within the scope of the appended claims, the inventionmay be practiced other than as specifically described. For that reasonthe appended claims should be studied to determine true scope andcontent.

What is claimed:
 1. A case for a gas turbine engine comprising: aplurality of distinct case sections in axial series, the case sectionsincluding, in axial order, a flange section, a forward shell section, acontainment section, and an aft shell section, the forward shellsection, the containment section, and the aft shell section being formedof a plurality of unidirectional roving fiber layers and a plurality ofnon-crimp fabric layers, and the flange section being formed of a secondplurality of non-crimp fabric layers, wherein the plurality ofunidirectional roving fiber layers do not have stitching or weaves; aballistic liner attached with the containment section; and a fiberglasslayer encapsulating the plurality of unidirectional roving fiber layers,the plurality of non-crimp fabric layers, and the second plurality ofnon-crimp fabric layers.
 2. The case for a gas turbine engine as recitedin claim 1, wherein at least one of the plurality of unidirectionalroving fiber layers is at a 0 degree direction with respect to an engineaxis.
 3. The case for a gas turbine engine as recited in claim 1,wherein at least one of the plurality of unidirectional roving fiberlayers is at a 90 degree direction with respect to an enginelongitudinal axis.
 4. The case for a gas turbine engine as recited inclaim 1, wherein each of the plurality of non-crimp fabric layersincludes a first ply at a +θ orientation and a second ply at a −θorientation relative to the engine longitudinal axis.
 5. The case for agas turbine engine as recited in claim 4, wherein θ is between 0-80degrees with respect to an engine longitudinal axis.
 6. The case for agas turbine engine as recited in claim 1, wherein the containmentsection is approximately 0.25-1.0 inches thick.
 7. The case for a gasturbine engine as recited in claim 1, wherein the ballistic linerincludes a plurality of woven aramid fibers impregnated with resin.
 8. Acase for a gas turbine engine comprising: a plurality of distinct casesections in axial series, the case sections including, in axial order, aflange section, a forward shell section, a containment section, and anaft shell section, the forward shell section, the containment section,and the aft shell section being formed of a plurality of unidirectionalroving fiber layers and a plurality of non-crimp fabric layers, and theflange section being formed of a second plurality of non-crimp fabriclayers, wherein the plurality of unidirectional roving fiber layers donot have stitching or weaves; and a fiberglass layer encapsulating theplurality of unidirectional roving fiber layers, the plurality ofnon-crimp fabric layers, and the second plurality of non-crimp fabriclayers.
 9. The case for a gas turbine engine as recited in claim 8,wherein at least one of the plurality of unidirectional roving fiberlayers is at a 0 degree direction with respect to an engine axis, and atleast one of the plurality of unidirectional roving fiber layers is at a90 degree direction with respect to an engine longitudinal axis.
 10. Thecase for a gas turbine engine as recited in claim 8, wherein each of theplurality of non-crimp fabric layers includes a first ply at a +θorientation and a second ply at a −θ orientation relative to the enginelongitudinal axis.
 11. The case for a gas turbine engine as recited inclaim 10, wherein θ is between 0-80 degrees with respect to an enginelongitudinal axis.
 12. The case for a gas turbine engine as recited inclaim 11, wherein the containment section is approximately 0.25-1.0inches thick.
 13. The case for a gas turbine engine as recited in claim12, further comprising a ballistic liner attached with the containmentsection, and the ballistic liner includes a plurality of woven aramidfibers impregnated with resin.
 14. A gas turbine engine comprising: afan; a compressor section; a combustor; a turbine section; and a fancase surrounding the fan, the fan case including, a plurality ofdistinct case sections in axial series, the case sections including, inaxial order, a flange section, a forward shell section, a containmentsection, and an aft shell section, the forward shell section, thecontainment section, and the aft shell section being formed of aplurality of unidirectional roving fiber layers and a plurality ofnon-crimp fabric layers, and the flange section being formed of a secondplurality of non-crimp fabric layers, wherein the plurality ofunidirectional roving fiber layers do not have stitching or weaves, aballistic liner attached with the containment section, and a fiberglasslayer encapsulating the plurality of unidirectional roving fiber layers,the plurality of non-crimp fabric layers, and the second plurality ofnon-crimp fabric layers.